Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

3 hosts · 234 ms

HostCertsFirst seenLast seenDNS
r2-bike.com 22 2025-07-16 2026-10-03 ok
*.r2-bike.com 16 2026-04-24 2026-10-03 —
www.r2-bike.com 6 2025-07-16 2026-09-13 ok

Programmatic access, with DNS A records: API GET /v1/hosts/r2-bike.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/r2-bike.com.